1. Field of the Invention
This invention relates to a new clutch for a cooling fan of a motor vehicle and to a method of making such a clutch.
2. Prior Art Statement
It is known to applicant to provide a clutch for a cooling fan of a motor vehicle wherein the clutch comprises a shaft having a first end to be attached to a rotatable member of the motor vehicle and having a second end defined by a cylindrically shaped knurled portion and an adjacent second portion, the knurled portion having protuberances defined by slots formed in the exterior of the shaft, the knurled portion having an outer diameter and having an inner edge adjacent the second portion and an outer edge adjacent the first end, a bearing means having an inner race member press-fitted onto the knurled portion, a housing comprising a body member and a plate member secured together to form an enclosed chamber for holding a viscous fluid, the housing having means for mounting a fan, the body member having a central opening defined by structural means, the bearing means being disposed in the central opening of the body member and engaging the structural means such that the bearing means supports the body member and hence the housing for rotation, and a drive plate having a central opening defined by inner structure press-fitted onto the second portion of the shaft. For example, see the abandoned U.S. patent application, Ser. No. 490,798, filed May 2, 1983.
Also see U.S. Pat. Nos. 3,575,269 and 4,257,501 which disclose two different types of fan clutches for motor vehicles such as automobiles or trucks. In both types of fan clutches, a housing is formed by a body member and a plate member secured together to form an enclosed chamber for holding a viscous fluid. A shaft is provided for coupling the fan clutch to the engine of the vehicle. The shaft has a smooth surface at one end for rotatably supporting the drive plate of the fan clutch. The bearing is press-fitted onto the end of the shaft and supports the body member and hence the housing for rotation. The drive plate, located in the chamber, also is press-fitted onto the end of the shaft.